Sheet metal forming has been used in the industry for years for creating metal parts from a blank sheet metal, for example, automobile manufacturers and their suppliers produce many of the parts using sheet metal forming. One of the most used sheet metal forming processes is referred to as draw forming or stamping.
In general, after a blank sheet metal is formed into a drawn part (or stamped sheet metal) that includes a trimmed portion (desired-to-be-kept portion or sometimes referred to as parent portion) and at least one scrap portion (unwanted extra materials). At least one scrap portion is trimmed or cut away in a trimming operation to produce the trimmed portion, which may or may not be the finished product depending upon whether the drawn part is partially or completely drawn. It also depends upon whether the trimming operation is an intermediate one or a final one. Trimming operation is done in a trim die with scrap chute to guide the resulting scrap portions away to scrap collectors. Trimming and the resulting scrap fall are some of the top factors or considerations in affecting efficiency and productivity of a sheet metal stamping manufacturing procedure. Difficult trimming conditions, such as those multiple direct trims, a mixture of direct and cam trims, and multiple cam trims involving bypass condition, can cause trimmed scraps to get stuck and not separated from the trim edge of upper trim steels or lower trim post. Inappropriate design of die structure and scrap chute can also slow down or prevent scraps from tumbling out or falling to scrap collectors. Smaller scrap pieces (especially aluminum) can sometimes shoot straight up, and gather in areas of the die structure. All these problems result in shutdowns of stamping presses, reducing stroke-per-minute and causing hundreds of thousands of dollars in lost productivity.
With advent of computer technology, manufacturing procedure can be numerically simulated using computer aided engineering analysis (e.g., finite element analysis (FEA)). Based on the numerically-simulated results, a particular physical metal forming operation can be set up accordingly.
For example, FEA has been used for numerically simulating manufacturing process of sheet metal forming particularly including trimming operations. However, prior art approaches required many manual steps that are ad hoc, cumbersome therefore error-prone. In one of the prior art approaches, separate computerized model of each scrap portion needs to be manually created, and often required a priori expertise.
It would be desirable to have improved methods and systems for conducting a time-marching simulation of scrap trimming operations in metal forming.